The present invention relates to a folding apparatus in a web-fed rotary printing press.
In web-fed rotary printing presses, the material webs to be printed are pulled off a paper roll and, upon printing in one or more printing units, are fed to a folding apparatus in which the webs are cut into individual signatures by a cutting device and subsequently folded crosswise by a folding blade arranged on a folding blade cylinder.
In this context, it is necessary for the signatures to be always guided in a controlled manner during the cutting process and the subsequent transport to and/or on the folding blade cylinder or on a transfer cylinder of the folding apparatus to ensure that the leading edges of the signatures are not folded over and that the folds are located exactly at the intended positions.
In this context, it is known from U.S. Pat. No. 5,484,379 to arrange a first cutting cylinder before a folding blade cylinder, the cutting cylinder having a segmented cutting blade which is provided with gaps and which makes a plurality of spaced apart first partial cuts in the material web. In the process, the signatures are carried by endlessly rotating conveyer belts during the cutting operation and during the subsequent transport to and on the folding blade cylinder, the conveyer belts passing through the gaps and partially wrapping around the downstream folding blade cylinder. In a second cutting operation, a further cutting cylinder, which similarly carries a cutting blade provided with further gaps, makes second partial cuts in the web, which complement the first partial cuts into a continuous cut. In this process, the signatures are similarly carried by a plurality of further conveyer belts passing through the further gaps in the second cutting blade; the folding blade cylinder serving as a supporting element or anvil element for the second cutting blade. Apart from the large number of component parts, the first and second partial cuts made in the material web lead to the problem that the cut edges of the signatures are not smooth along the entire length, even in the case of minor changes in position of the signatures after the first cutting operation, and therefore generally require post-processing.